Optical communication systems transfer optical signals from a transmitter (TX) of one system to a receiver (RX) of another system. In general, optical signals can be transmitted through an optical fiber at relatively high data rates and relatively low signal attenuation, therefore making such data transmission suitable for, e.g., telephony, Internet and cable television. In general, optical signals can be sent through an optical fiber in either direction from one end of the optical fiber to another. For example, a dedicated source of light and a TX on one end of the optical fiber can be in communication with a corresponding RX on the opposite end of the optical fiber.
FIG. 1 schematically illustrates an optical communication system 10. A transceiver 12 includes a laser L, a modulator M and a demodulator (also known as a detector) D. The laser L generates an optical beam that is suitably modulated by the modulator M into a stream of optical signals 13. A transmitter TX routes the stream of optical signals 13 to an optical fiber 14. Due to relatively low signal attenuation, the optical fiber 14 can transfer signals over long distances, e.g., tens or hundreds of kilometers. At the other side of the optical fiber 14, the optical signals 13 are received by a receiver RX and demodulated by a demodulator D of a transceiver 16. When the optical communication system 10 sends optical signals 15 in the opposite direction, i.e., from the transceiver 16 to the transceiver 12, a laser L of the optical transceiver 16 generates an optical beam, a modulator M modulates the optical beam into a stream of optical signals 15, and a transmitter TX routes the optical signals through the optical fiber 14 back toward the transceiver 12.
However, the optical communication system 10 includes a relatively large number of components, including two lasers. In conventional optical communication systems, the lasers are typically the most expensive components and can also consume significant amounts of energy to operate. Furthermore, the relatively high complexity of these conventional optical communication systems results in the correspondingly high number of failures that, in turn, increase system downtime and repair cost. Accordingly, there remains a need for simple, low cost and high availability optical communication systems.